Display device
A display device is disclosed, which includes: a first substrate; an oxide semiconductor layer disposed on the first substrate; a silicon semiconductor layer disposed on the first substrate; and a capacitor including a first conductive component and a second conductive component, wherein the first conductive component is electrically connected to the oxide semiconductor layer and the second conductive component is electrically connected to the silicon semiconductor layer.
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This application claims the benefit of filing date of U.S. Provisional Application Ser. No. 62/429,162 filed Dec. 2, 2016 under 35 USC § 119(e)(1).
This application is a continuation (CA) of U.S. patent application for “Display device”, U.S. application Ser. No. 16/402,478 filed May 3, 2019, U.S. application Ser. No. 16/402,478 is a continuation of U.S. application Ser. No. 15/486,336 filed Apr. 13, 2017, and the subject matter of which is incorporated herein by reference.
BACKGROUND 1. FieldThe present disclosure relates to a display device and, more particularly, to a display device with a transistor comprising an oxide semiconductor layer with various element concentrations.
2. Description of Related ArtWith the continuous advancement of technologies related to displays, all the display panels are now developed toward compactness, thinness, and lightness. This trend makes thin displays, such as liquid crystal display panels, organic light-emitting diode display panels and inorganic light-emitting diode display panels, replacing cathode-ray-tube displays as the mainstream display devices on the market. Applications of thin displays are numerous. Most electronic products for daily use, such as mobile phones, notebook computers, video cameras, still cameras, music displays, mobile navigators, and TV sets, employ such display panels.
While liquid crystal display devices and organic light-emitting diode display devices are popular on the market; in which LCD display devices particularly enjoy technical maturity, manufacturers pay even more effort to improve display devices in terms of display quality thereby answering to ongoing technical development of display devices and consumers' increasing demands.
The thin film transistor (TFT) structure can be polycrystalline silicon thin film transistors (TFT) featuring high carrier mobility, or metal oxide thin film transistors (TFT) featuring low leakage. There are presently no displays combining these two types of transistors because the manufacturing processes for making the two are not quite compatible, making the overall manufacturing of such display devices complicated (such as by requiring more times of chemical vapor deposition).
In view of this, a need exists for an improved and simplified process for manufacturing a thin film transistor (TFT) substrate that has both a polycrystalline silicon thin film transistor (TFT) and a metal oxide thin film transistor (TFT).
SUMMARYAn object of the present disclosure is to provide a display device comprising a transistor with an oxide semiconductor layer, wherein the atomic percentages of elements in the oxide semiconductor layer are adjusted to provide improved electrical performance or reliability.
In one aspect of the present disclosure, the display device comprises: a first substrate; a first transistor disposed over the first substrate, wherein the first transistor comprises an oxide semiconductor layer and a second transistor disposed over the first substrate, wherein the second transistor comprises a silicon semiconductor layer, wherein the oxide semiconductor layer comprises indium, gallium, and oxygen; and a ratio of an atomic percentage of oxygen to a sum of atomic percentages of indium and gallium in the oxide semiconductor layer is greater than or equal to 1 and less than or equal to 3.
In another aspect of the present disclosure, the display device comprises: a first substrate; and a first transistor disposed over the first substrate, wherein the first transistor comprises an oxide semiconductor layer, wherein the oxide semiconductor layer comprises indium, gallium, zinc, and oxygen; a ratio of an atomic percentage of oxygen to a sum of atomic percentages of indium and gallium in the oxide semiconductor layer is greater than or equal to 1 and less than or equal to 3; and a ratio of a sum of atomic percentages of indium and gallium to an atomic percentage of zinc in the oxide semiconductor layer is greater than or equal to 1 and less than or equal to 3.
In the display device of the two above aspects, the atomic percentages of elements in the oxide semiconductor layer of the first transistor are adjusted. More specifically, the ratio of the atomic percentage of oxygen to the sum of the atomic percentages of indium and gallium in the oxide semiconductor layer is greater than or equal to 1 and less than or equal to 3, i.e. 1≤O/(In+Ga)≤3.
When the atomic percentages in the oxide semiconductor layer are within the above range, the first transistor comprising the oxide semiconductor layer has the improved electrical performance and reliability.
Other objects, advantages, and novel features of the disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The following embodiments when read with the accompanying drawings are made to clearly exhibit the above-mentioned and other technical contents, features and effects of the present disclosure. Through the exposition by means of the specific embodiments, people would further understand the technical means and effects the present disclosure adopts to achieve the above-indicated objectives. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art all equivalent changes or modifications which do not depart from the concept of the present disclosure should be encompassed by the appended claims.
Furthermore, the ordinals recited in the specification and the claims such as “first”, “second” and so on are intended only to describe the elements claimed and imply or represent neither that the claimed elements have any proceeding ordinals, nor that sequence between one claimed element and another claimed element or between steps of a manufacturing method. The use of these ordinals is merely to differentiate one claimed element having a certain designation from another claimed element having the same designation.
Furthermore, the ordinals recited in the specification and the claims such as “above”, “over”, or “on” are intended not only directly contact with the other first substrate or film, but also intended indirectly contact with the other first substrate or film.
EmbodimentIn the display device of the present embodiment, the first substrate 1 is provided with plural pixel units 15. One of these pixel units may be designed as, for example, the equivalent-circuit diagram as shown in
As shown in
In addition, as shown in
As shown in
Hence, after the aforementioned process, the display device of the present embodiment is obtained, which comprises: a first substrate 1; and a first transistor disposed over the first substrate 1, wherein the first transistor comprises an oxide semiconductor layer 45.
In the present embodiment, the oxide semiconductor layer 45 comprises indium, gallium, zinc, and oxygen. The electrical performance of an IGZO TFT is related to the oxygen concentration of the metal oxide layer, as when the oxygen concentration of the metal oxide layer is high, the conductivity of the metal oxide layer is close to a conductivity of an insulator. On the contrary, when the oxygen concentration of the metal oxide layer is low, the conductivity of the metal oxide layer is close to a conductivity of a conductor. Herein, a ratio of an atomic percentage of oxygen to a sum of atomic percentages of indium and gallium in the oxide semiconductor layer 45 is greater than or equal to 1 and less than or equal to 3, i.e. 1≤O/(In+Ga)≤3. When the oxygen concentration of the IGZO layer is in the above ratio, the IGZO TFT has better electrical characteristics. Additionally, a ratio of a sum of atomic percentages of indium and gallium to an atomic percentage of zinc in the oxide semiconductor layer 45 (especially, in the first region 451) is greater than or equal to 1 and less than or equal to 3, i.e. 1≤(In+Ga)/Zn≤3. When ratio of the concentration of indium, gallium and zinc is in the above range, the IGZO TFT has better voltage stress and current stress performance. Therefore, the IGZO TFT has good reliability.
In addition, the oxide semiconductor layer 45 has a first region 451 and a second region 452, and the first region 451 is between the second region 452 and the first substrate 1. Herein, the first region 451 and the second region 452 can be prepared by using two targets with identical components but different atomic concentrations; or prepared by introducing compositions with identical components but different atomic ratios. However, the present disclosure is not limited to.
In the present embodiment, the first region 451 and the second region 452 are two different layers made of IGZO material with identical components but different atomic concentrations. In another embodiment, the first region 451 and the second region 452 can be two region in the same layer made of IGZO. In the TFT operation period, the current flow occurs in the first region 451, hence the first region 451 suffers voltage stress and current stress, resulting in threshold voltage shift after a period of operation. When IGZO layer has higher indium concentration and higher zinc concentration in the first region 451, the IGZO TFT has higher current and better stability. Besides, the second region 452 is damaged during the etching process for forming the source electrode and drain electrode. When IGZO layer has higher gallium concentration in the second region 452, it provides additional protection for the IGZO layer from damage by following etching process. Therefore the first region 451 is a zinc-rich and indium-rich region, and the second region 452 is a gallium-rich region. More specifically, a concentration of indium in the first region 451 is greater than a concentration of indium in the second region 452; a concentration of zinc in the first region 451 is greater than a concentration of zinc in the second region 452; and a concentration of gallium in the first region 451 is less than a concentration of gallium in the second region 452. When the oxide semiconductor layer 45 comprises the above first region 451 and the above second region 452, the obtained IGZO thin film transistor can have improved electrical performance or reliability.
Particularly, the first region 451 of the oxide semiconductor layer 45 forms the TFT carrier channel. If the first region 451 is the zinc-rich and indium-rich region, the mobility of the semiconducting carrier in IGZO TFT channel can be increased.
In addition, as shown in
In the process for prepared the bottom gate structured IGZO TFT, the first source electrode 46 and the first drain electrode 47 are formed via a dry-etching process or other processes after forming the oxide semiconductor layer 45. Hence, the topmost layer of the oxide semiconductor layer 45 (i.e. the second region 452) may be deteriorated due to the sequential dry-etching process or other processes for forming the first source electrode 46 and the first drain electrode 47. Since gallium in IGZO forms a strong chemical bond with oxygen ions, the formed strong chemical bond can stabilize amorphous state of the IGZO material and reduce the formation of oxygen deficiencies. Hence, in the display device of the present embodiment, the second region 452 is designed to be a gallium-rich region to increase the process durability and electrical stability thereof.
Furthermore, when the second region 452 is a gallium-rich region, the current leakage of the IGZO TFT can be reduced, and good ohmic contact between the second region 452 and the first source electrode 46/the first drain electrode 47 can be achieved. In addition, because the zinc and indium concentrations in the second region 452 are reduced, the current leakage and oxygen deficiencies occurred in the IGZO TFT can also be decreased.
As shown in
Moreover, as described above, both the transistor comprising a silicon semiconductor layer (for example, LTPS TFT) and the transistor comprising an oxide semiconductor layer (for example, IGZO TFT) are comprised in the display device of the present embodiment. The mobility of the LTPS TFT is approximately ten times of the mobility of the IGZO TFT. When the oxide semiconductor layer 45 of the IGZO TFT has the above two layered structure, not only the low current leakage property of the IGZO TFT can be maintained, but also the mobility of the IGZO TFT can further be improved. Therefore, the mobility of the IGZO TFT can more match with the mobility of the LTPS TFT.
As shown in
The display device obtained in the aforementioned embodiment is examined with TEM-EDX equipment; and the IGZO composition of the oxide semiconductor layer is analyzed via a line scan analysis mode. The analysis results are shown in
For the TEM-EDX analytical method, the TFT is cut to form a slit, and a cross-sectional image of the TFT is obtained. Next, the scanning step of the TEM-EDX is commenced, specifically the scanning of the line L1-L1′ and the line L2-L2′ are started. The scanning line of L1-L1′ is made at the middle of the channel area of the TFT, to scan the atomic concentration of the semiconductor layer in the TFT. To further understand the relation of the semiconductor layer and its surrounding interface of insulating layers, the line L1-L1′ is scanned starting at the gate insulating layer, into the first region and the second region of the semiconductor layer, and ends at the passivation layer. While the line L2-L2′ is scanned to further understand the interface interaction of the semiconductor and the contacting source/drain electrodes, so the line L2-L2′ is made at one of the source/drain electrode ends of the TFT. The line L2-L2′ starts at the gate insulating layer, into the first region and the second region of the semiconductor layer, and further into the metal layer of the source/drain electrode, before it ends at the passivation layer.
The atomic percentages (at. %) of the elements comprised in the channel region of the oxide semiconductor layer are listed in the following Table 1. It should be noted that the values shown in the table are the average values of the atomic percentages of the elements measured at the middle-thickness portion of the layers. The material analysis can't get exact concentration of each element. As shown in Table 1, the measured atomic percentage of indium, gallium and zinc are 16.34%, 19.22% and 17.28% in the first region. However, as shown in
In addition, as shown in
A display device made as described in any of the embodiments of the present disclosure as described previously may be integrated with a touch panel to form a touch display device. Moreover, a display device or touch display device made as described in any of the embodiments of the present disclosure as described previously may be applied to any electronic devices known in the art that need a display screen, such as displays, mobile phones, laptops, video cameras, still cameras, music players, mobile navigators, TV sets, and other electronic devices that display images.
Although the present disclosure has been explained in relation to its embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the disclosure as hereinafter claimed.
Claims
1. A display device, comprising:
- a first substrate;
- a first oxide semiconductor layer and a second oxide semiconductor layer disposed on the first substrate;
- a silicon semiconductor layer disposed on the first substrate; and
- a capacitor including a first conductive component and a second conductive component,
- wherein the first conductive component is disposed on the first substrate and is electrically connected to the silicon semiconductor layer, and the second conductive component is disposed on the first conductive component and is physically connected to the first oxide semiconductor layer and the second oxide semiconductor layer, and
- wherein the second conductive component is at least partially overlapped with the first oxide semiconductor layer.
2. The display device of claim 1, wherein the first oxide semiconductor layer is disposed on the first silicon semiconductor layer.
3. The display device of claim 1, further comprising a first gate electrode disposed on the first substrate, wherein the first oxide semiconductor layer is disposed on the first gate electrode.
4. The display device of claim 3, further comprising a gate insulating layer disposed between the first gate electrode and the first oxide semiconductor layer, wherein a maximum atomic percentage of oxygen in the gate insulating layer is greater than a maximum atomic percentage of oxygen in the first oxide semiconductor layer.
5. The display device of claim 4, wherein the gate insulating layer comprises silicon oxide.
6. The display device of claim 1, further comprising a gate electrode disposed on the first substrate, wherein the gate electrode is disposed on the silicon semiconductor layer.
7. The display device of claim 1, further comprising a passivation layer disposed on the first oxide semiconductor layer, wherein the passivation layer comprises silicon oxide.
8. The display device of claim 1, wherein the first oxide semiconductor layer is an indium gallium zinc oxide (IGZO) layer.
9. The display device of claim 1, wherein the silicon semiconductor layer is a low-temperature polycrystalline silicon semiconductor layer.
10. The display device of claim 1, further comprising a display medium layer electrically connected to the first oxide semiconductor layer, wherein the display medium layer is an organic light-emitting diode unit.
11. The display device of claim 1, wherein the first substrate comprises a flexible substrate.
12. The display device of claim 1, further comprising a display region and a peripheral region adjacent to the display region, wherein a driver circuit is disposed in the peripheral region and comprises the silicon semiconductor layer.
13. The display device of claim 1, wherein the first conductive component is not overlapped with the second oxide semiconductor layer.
14. The display device of claim 1, further comprising a display region and a peripheral region adjacent to the display region, wherein the first oxide semiconductor layer and the second oxide semiconductor are disposed in the display region, and the silicon semiconductor layer is disposed in the peripheral region.
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Type: Grant
Filed: Nov 5, 2020
Date of Patent: Jun 6, 2023
Patent Publication Number: 20210082968
Assignee: INNOLUX CORPORATION (Miao-Li County)
Inventors: Chandra Lius (Miao-Li County), Nai-Fang Hsu (Miao-Li County)
Primary Examiner: Samuel Park
Application Number: 17/090,223
International Classification: H01L 29/786 (20060101); H01L 27/12 (20060101); G06F 3/041 (20060101); G02F 1/1333 (20060101); G02F 1/1343 (20060101); H01L 27/32 (20060101); H01L 29/24 (20060101); H01L 29/423 (20060101); G02F 1/1368 (20060101); H01L 29/49 (20060101);